JOURNAL OF TRANSPORTATION RESEARCH
Year:2015 | Volume:11 | Issue:4 (41)|Papers Count:6

Traffic signal using at crosswalks directly effects on the safety of pedestrian and vehicles delay. Considering the importance of non- compliance traffic signals by some pedestrians and the effect of this problem on traffic signal setting has been discussed in this paper. First the relationship between duration of pedestrian green phase and pedestrian violation introduced. The problem developed a traffic signal optimization strategy that considers both vehicles and pedestrian. The objective of the method is to minimize the average vehicle delay under constraint of pedestrian green phase. The new algorithm is introduced to solve the problem. Finally, numerical example is solved by this algorithm to show the efficient of algorithm.

The heterogeneous fixed fleet vehicle routing problem (HFFVRP) is one of the most significant extension problems of the Vehicle Routing Problem (VRP). The HFFOVRP is the problem of designing optimal delivery from a given depot in order to satisfy the demand of the customer population by a fleet of a fixed number of vehicles. Because the solving of this problem which has numerous applications in industrial and service problems is difficult, a column generation (CG) algorithm for solving HFFVRP is proposed in this paper. The proposed algorithm is tested on 16 standard instances involving 10 to 50 customers. The computational results show that the CG results are better than results of exact algorithm for solving the HFFVRP within a comparatively shorter period of time.

Many roads in forest areas are located along the steep hills. The cut and fill method is currently used for construction of these roads. Settlement or consolidation in not enough compacted soil or creep in down slope, can lead to subsidence and cracks in roads. General methods for solving settlement related problems such as reconstruction, retaining structure and … are expensive. Deep patch method is a low- cost method for increasing the stability of slopes. In this method, the upper parts of the subsided area are excavated and replaced with reinforcement materials such as Geo grid in accordance with compacted soil. In this paper, limit equilibrium method has been implemented for determining the safety factor of a planar slip surface in a slope. Furthermore, graphs for determining safety factor of reinforced soil slope with Geo synthetics have been proposed.

One of the key parameters to design flexible pavements is the resilient modulus of HMA. For determining the resilient modulus of asphalt concrete, commonly the indirect tension test has been used which includes loading the sample with a haversine pulse with duration of 0.1s and a rest period of 0.9 seconds at different temperatures. Due to the viscoelastic nature of asphalt mixes and the influence of loading time, rest period and loading waveform on the resilient modulus of HMA, this paper deals with the effect of loading time, rest period and loading waveform on the resilient modulus of HMA. To reach this end, the resilient modulus test using the indirect tension test method was carried out on the asphalt mix specimens prepared with both unmodified and SBS-modified bitumen. Then, the resilient modulus of specimens were determined using haversine and square loading at three different temperatures of 5, 25 and 40oC by varying the duration and rest period of applied load and results are compared to each other. Some models have been presented to predict the resilient modulus of HMA by regression analysis. According to the experimental results, the most significant factors to enhance the resilient modulus of HMA were the reduction of temperature, increase of loading time and SBS content in asphalt mixture, and finally the reduction of the rest period to loading time ratio. The most important factors to decrease the resilient modulus of HMA were increase of temperature; change the haversine waveform to square waveform, and increase of loading time.

Setting up a work zone, always make tribulations for traffic flow and spend considerable amounts of useful time, capital and vigor of commuters. The most important suppliants related parameters, that a traffic engineer must consider in a work zone design, are, safety, travel time, costs, delay time, fuel consumptions, pollution and etc. Nowadays, many efforts take place to decrease undesirable effects of a work zone on the traffic flow, so that not to waste driver’s time, national resources and wealth, because of reduction of capacity of roads in work zones. In this research, to achieve an optimum length and distances between work zones, to minimize delay time of travel, different volumes of traffic flow, truck percentages, number of lanes of road and number of closed lanes was considered. After a calibration procedure, a general software simulation of work zones was carried out, by Aimsun program. With using the outputs of Aim sun, a Mat lab model has been developed to find the best form of the work zone geometry.

Carrying passenger and freight safely in all aspects to their destinations is of utmost importance for railway administrators. Undergoing safety procedures and developing safety systems requires awareness of what is causing unsafe conditions, which can be done by learning from the past. The department of Signaling & Communication is one of the most important departments in Iranian Railways, which carries out the control of failures in signaling and communication equipment and thus provides the safe condition for train movements. This research has been performed to analyze past failures data of the signaling and communication equipment in Iranian Railway (RAI). For this purpose, some 30, 235 failure records from the RAI signaling and communication database were selected from years 2011 and 2012. The Apriori association rule technique, C5.0 decision tree technique, and CRISP-DM methodology are applied. Determining the rules and the relationships among the system attributes and predicting their values, it will be possible to take necessary actions to prevent or mitigate the failures and thus provide the safety in rail transportation.